One of the newest and most intriguing areas of nutrition investigation involves food components called phytochemicals. Phytochemicals, such as isoflavones and their derivatives, are found only in plants, and although they are not classified as nutrients, they profoundly affect our health. See, for example, xe2x80x9cPhytochemicals, A new paradigmxe2x80x9d edited by W. R. Bidlack et al., published by Technomic publishing Co., Inc, 1998.
The discovery of phytochemicals has caused the dawning of a new era in nutrition. The phytochemicals found in grains, such as soybeans, are of particular interest. Soybeans and the products made from them offer a unique approach to lowering the incidence of many chronic diseases such as cancer. See, for example, Journal of Agricultural Food Chemistry, 42, 1666 (1994); i.d., 43, 1184 (1995). Recently, research shows that consuming just one serving of soy foods a day may be enough to obtain the benefits of these phytochemicals. (See xe2x80x9cThe simple soybean and your healthxe2x80x9d by M. Messina et al., published by Avery publishing Group, Garden City Park, N.Y., 1994).
Many people, however, do not like to eat soy foods because of their smell, taste, and texture. One way to obviate the dislike of soy foods would be to take soybean isoflavones as dietary supplements. Unfortunately, soybean isoflavones and their derivatives have not been utilized as dietary supplements because of their low solubility in water. See xe2x80x9cGenesteinxe2x80x9d by R. Elkins, published by Woodland Publishing, Pleasant Grove, Utah 1998.
In one aspect, the invention features a water-soluble soybean-based dry or wet extract including one or more isoflavone derivatives of the formula: 
where R1 is hydrogen or hydroxy, R2 is hydrogen or methoxy, R3 is hydrogen or COxe2x80x94R4, R4 being methyl or carboxymethyl. The water-soluble soybean-based extract, in dried form, includes from about 5 to about 50 parts by weight of isoflavone derivatives and has a solubility from about 10 mg/ml to about 1,000 mg/ml in water at about 25xc2x0 C. Examples of isoflavone derivatives present in the water-soluble soybean-based extract include daidzin, genistin, glycitin, 6xe2x80x3xe2x80x94Oxe2x80x94 acetyldaidzin, 6xe2x80x3xe2x80x94Oxe2x80x94 acetylgenistin, 6xe2x80x3xe2x80x94Oxe2x80x94 acetylglycitin, 6xe2x80x3xe2x80x94Oxe2x80x94 malonyldaidzin, 6xe2x80x3xe2x80x94Oxe2x80x94 malonylgenistin, or 6xe2x80x3xe2x80x94Oxe2x80x94 malonylglycitin.
The water-soluble soybean-based extract of this invention includes one or more isoflavone derivatives, e.g., an isoflavone glycoside, which complex with other components contained in soybeans to unexpectedly enhance their solubility in water.
In another aspect the invention features a method of preparing a water-soluble soybean-based extract. The method includes mixing a pulverized crude soybean extract with water, heating the mixture, adding a coagulant to the mixture to form a suspension, heating the suspension, and collecting the supernatant to obtain a water-soluble soybean-based extract.
The water-soluble soybean-based extract of this invention has a pleasant taste and smell, and exhibits desirable composition and performance when used as an ingredient in any food product. For example, the water-soluble soybean-based extract can be combined with a food product such as milk, tea, soft drink, juice, coffee, seasoning, cereal, water, beer, cookies, chewing gum, chocolate, or soup.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.